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12. Knowledge Sources / B. Perception / 4. Sense Data / c. Unperceived sense-data

[the status of sense-data when not perceived]

4 ideas
When sense-data change, there must be indistinguishable sense-data in the process [Russell]
     Full Idea: In all cases of sense-data capable of gradual change, we may find one sense-datum indistinguishable from another, and that indistinguishable from a third, while yet the first and third are quite easily distinguishable.
     From: Bertrand Russell (Our Knowledge of the External World [1914], 5)
     A reaction: This point is key to the sense-data theory, because it gives them independent existence, standing between reality and subjective experience. It is also the reason why they look increasingly implausible, if they may not be experienced.
We do not know whether sense-data exist as objects when they are not data [Russell]
     Full Idea: We do not know, except by means of more or less precarious inferences, whether the objects which are at one time sense-data continue to exist at times when they are not data.
     From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §II)
     A reaction: Note that he actually refers to sense-data as 'objects'. It shows how thoroughly reified they are in his theory if they have the possibility of independent existence. This invites the question 'what are they made of?'
'Sensibilia' are identical to sense-data, without actually being data for any mind [Russell]
     Full Idea: I shall give the name 'sensibilia' to those objects which have the same metaphysical and physical status as sense-data without necessarily being data to any mind.
     From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §III)
     A reaction: This is his response to the problem of whether sense-data can exist independently of experience, which was unclear in 1912. Presumably sensibilia are objects which are possible sources of experience, but that seems to cover most objects.
Ungiven sense-data can no more exist than unmarried husbands [Russell]
     Full Idea: We cannot ask, 'Can sense-data exist without being given?' for that is like asking, 'Can husbands exist without being married?'
     From: Bertrand Russell (The Relation of Sense-Data to Physics [1914], §III)
     A reaction: This follows hard on Idea 6460, which introduces the idea of 'sensibilia' for things which are like sense-data, but are not 'given'. This is a new distinction in 1914, which he had not made in 1912.